Leishmania are obligate intracellular parasites that cause a wide range of diseases such as cutaneous, mucocutaneous and visceral leishmaniasis. Over 12 million people currently suffer from these diseases, and approximately 2 million are infected annually, making this a major global health problem. Cutaneous leishmaniasis (CL) manifests as localized skin lesions which may heal or become chronic leading to significant tissue destruction and disfigurement. There is a clear need for a topical treatment against CL because current therapy for this disease involves daily injections of antimonials (GlucantimeTM or PentostamTM) for prolonged periods, which is toxic and has poor patient compliance. In the Yucatan Peninsula, Mayan traditional healers use Pentalinon andrieuxii root for topical treatment of CL, which suggests that P. andrieuxii can be a potential source of novel drugs to treat leishmaniasis. In our preliminary studies, we have found that hexane extract of Pentalinon andrieuxii root (PARE) exhibits potent antileishmanial activity. Our data indicate that PARE kills Leishmania in vitro as efficiently as GlucantimeTM. PARE is not toxic to mammalian cells and it also increases leishmanicidal activity in macrophages. This project will seek to isolate and characterize antileishmanial compound(s) in PARE using activity guided fractionation and standard analytical methods (Aim 1) and to test their leishmanicidal activity against intracellular Leishmania within mouse and human macrophages (Aim 2). We hypothesize that antileishmanial molecules in PARE exert direct cytotoxic activity against parasites as well as regulate activity of immune cells such as macrophages. Our team is uniquely poised to perform these studies due to complementary expertise in leishmaniasis (Satoskar), and phytochemistry and natural products development (Kinghorn). Our studies are important because they will identify novel antileishmanial molecules in PARE and provide clear insights into the mechanisms by which these molecules mediate their activity, which will be important for future clinical applications and drug development. In addition, these studies will provide insights into mechanisms by which these molecules enhance macrophage function and leishmanicidal activity. Together, these data will lay the foundation for a latter RO1 application focused on a more complete study of PARE-derived active components in local or systemic treatment of different forms of leishmaniasis as well as diseases caused by other trypanosomatids and their mechanism(s) of action. PUBLIC HEALTH RELEVANCE The overall goal of this project is to isolate and characterize novel anti-Leishmania compounds from the roots of plant Pentalinon andrieuxii.